/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

using System;

namespace DotnetPark.NLucene.Util
{
	/// <summary>
	/// A simple class for number conversions.
	/// </summary>
	public class Number
	{
		/// <summary>
		/// Min radix value.
		/// </summary>
		public const int MIN_RADIX = 2;
		/// <summary>
		/// Max radix value.
		/// </summary>
		public const int MAX_RADIX = 36;

		private const string digits = "0123456789abcdefghijklmnopqrstuvwxyz";

		/// <summary>
		/// Converts a number to string in the specified radix.
		/// </summary>
		/// <param name="i">A number to be converted.</param>
		/// <param name="radix">A radix.</param>
		/// <returns>A string representation of the number in the specified redix.</returns>
		public static string ToString(long i, int radix)
		{
			if (radix < MIN_RADIX || radix > MAX_RADIX)
				radix = 10;

			char[] buf = new char[65];
			int charPos = 64;
			bool negative = (i < 0);

			if (!negative) 
			{
				i = -i;
			}

			while (i <= -radix) 
			{
				buf[charPos--] = digits[(int)(-(i % radix))];
				i = i / radix;
			}
			buf[charPos] = digits[(int)(-i)];

			if (negative) 
			{
				buf[--charPos] = '-';
			}

			return new String(buf, charPos, (65 - charPos)); 
		}

		/// <summary>
		/// Parses a number in the specified radix.
		/// </summary>
		/// <param name="s">An input string.</param>
		/// <param name="radix">A radix.</param>
		/// <returns>The parsed number in the specified radix.</returns>
		public static long Parse(string s, int radix)
		{
			if (s == null) 
			{
				throw new ArgumentException("null");
			}

			if (radix < MIN_RADIX) 
			{
				throw new NotSupportedException("radix " + radix +
					" less than Number.MIN_RADIX");
			}
			if (radix > MAX_RADIX) 
			{
				throw new NotSupportedException("radix " + radix +
					" greater than Number.MAX_RADIX");
			}

			long result = 0;
			long mult = 1;

			s = s.ToLower();
			
			for(int i=s.Length-1; i>=0; i--)
			{
				int weight = digits.IndexOf(s[i]);
				if(weight == -1)
					throw new FormatException("Invalid number for the specified radix");

				result += (weight * mult);
				mult *= radix;
			}

			return result;
		}
	}
}
